The invention relates to a method and an apparatus for opening prefabricated (tubular) pouches, as well as to a method and an apparatus for filling prefabricated (tubular) pouches, which includes a method and an apparatus for opening such pouches.
For numerous reasons, e.g. relating to material and cost saving, as well as environmental considerations, nowadays efforts are often made to replace the hitherto widely used tin cans by pouches, which can be manufactured with a much smaller use of material.
The reason why such pouches have only been used with hesitation and substantially only when the quantities to be packed are very small is that the handling of prefabricated pouches, whilst maintaining a specific shape (dimensional stability) encounters difficulties, which more particularly applies to the opening step, which precedes filling and sealing.
In a prior art installation, the opening of prefabricated pouches in planar form, which are generally rectangular and have a circumferential seal and an opening zone, has taken place in that a pouch is gripped by grippers at its two lateral edges adjacent to the opening zone and movement towards one another takes place by a certain extent so that the pouch can be opened.
This method is disadvantageous in two respects. On the one hand the opening of a pouch by moving together the lateral edges is only possible with relatively small dimensions, because otherwise the pouch would merely sag without opening, and on the other, due to the elasticity of the sealing seams, the pouch can only be opened to a relatively limited extent, which leads to a correspondingly small, maximum filling quantity.
EP-0 844 179 discloses a method and an apparatus for opening prefabricated pouches, wherein opening of the pouches is realized by use of vacuum chambers being formed by two separable half-shells and presenting, when in the closed state, at an upper face an opening having an edge on which the opened pouch engages. The pouches are held by stationary rails covering the opening of the upper face. This known apparatus is used for opening and filling only of bags being able to stand alone in any upright position, not for pouches. Pouches require a special holding means.
Therefore the problem of the present invention is to provide a method and an apparatus for opening prefabricated pouches, with which the aforementioned disadvantages can be overcome and without limitation large pouches can be reliably opened and in particular more widely opened than was the case in the prior art.
From the method standpoint, this problem is solved by a method for the opening of prefabricated pouches, in which each pouch has a circumferential seal and an opening zone, with the steps: a) holding a pouch on a support; b) introducing the support with the pouch into a vacuum chamber, which has a first opening facing the opening zone of the pouch and which is connected to the environment, as well as a second opening remote from the opening zone; c) sucking air out of the vacuum chamber through the second opening, with a volume flow adequate for producing in the vacuum chamber a vacuum with respect to the environment, through which the pouch is opened; d) moving the support with the pouch held thereon out of the vacuum chamber.
Through the planned use of a vacuum and an air flow directed onto the pouch opening zone, the pouch is reliably and completely opened.
Preferably, the pouch is held on at least one first lateral edge. Appropriately, the pouch is displaceably held on a lateral edge facing the first lateral edge, so that opening is not impeded. The support preferably has a shell-like shape, which unilaterally corresponds to a completely opened pouch.
The vacuum chamber can be formed from two separable half-shells, which receive the support between them. Appropriately, the vacuum chamber is substantially cylindrical.
The first opening can be located in a first face of the vacuum chamber. The second opening can be located in a face opposite the first face.
Preferably, the arrangement is such that the opening pouch engages on the edge of the first opening and substantially closes the latter. Thus, due to the continuous suction of air through the second opening, an increasing vacuum is built up, which largely expands the pouch counter to the inherent elasticity or plastic deformability of the sealing seams.
The invention also relates to a method for filling prefabricated pouches, in which the pouches are opened, filled and closed, the method being characterized by an inventive method for opening prefabricated pouches.
From the apparatus standpoint, the set problem is solved by an apparatus for opening prefabricated pouches, in which each pouch has a circumferential seal and an opening zone, with a) at least one support for holding a pouch, b) a vacuum chamber for receiving the support, which has a first opening facing the opening zone of the pouch and is connected to the environment, and a second opening remote from the opening zone and c) a suction device connected to the second opening.
Preferably, the support has a first, fixed clamping device for the fixed holding of a pouch on a first lateral edge. Appropriately, the support has a second, movable clamping device for the movable holding of the pouch on a second lateral edge.
The support can have a shell-like shape, which unilaterally corresponds to a completely opened pouch.
The vacuum chamber is appropriately formed from a first and a second half-shell, which are separable from one another and receive the support between them. The vacuum chamber is appropriately substantially cylindrical. The first opening can be located in a first face of the vacuum chamber. The second opening can be located on a second face, which faces the first face.
Preferably, the arrangement is such that the opening pouch engages on the edge of the first opening and substantially closes the latter.
At least one support and at least one first half-shell of the vacuum chamber can be fitted to a first, rotating conveyor and at least one second half-shell to a second, rotating conveyor, the first and second conveyors running adjacent to one another within an opening area, so that within said opening area in each case one first half-shell and one second half-shell form a vacuum chamber.
The invention also relates to an apparatus for filling prefabricated pouches, with a filling device for filling empty pouches, a sealing device for sealing pouches, a removal device for removing filled pouches and a feed device for feeding empty pouches, characterized by an inventive apparatus for opening prefabricated pouches.